Many communications systems are known. Early communications systems were connection-based, in that a connection was physically established through the system between the communicating nodes. For example, in the early versions of the public switched telephone network (PSTN), users were provided a point-to-point connection to other users through switchboards, switches and trunks. More recently, the PSTN has employed multiplexed lines that are shared, through at least some part of the network, by multiple users, but which still provide a fixed amount of bandwidth and network capacity to each user for their voice data connection, these bandwidth and network capacities being selected as meeting the anticipated maximum requirements for a common telephone voice conversation, typically referred to as toll quality.
Data communications systems for “pure data” (i.e.—data transmissions other than voice) have also been built which are connectionless. Connectionless systems generally operate on a best effort and/or statistical basis to deliver data via a suitable, but not necessarily fixed, route between the users, at best effort transmission rates and/or error rates. An example of a connectionless system is a packet network such as the Internet wherein the network capacity is shared amongst the users.
More recently, attempts have been made to combine connectionless and connection-like services in a single communication system. For example, much interest has been expressed recently in Voice over IP (VoIP) through the Internet. However, it has proven difficult and/or costly to create a communication system which can meet both the connection-like requirements of VoIP (voice data requiring a moderate data rate and having some tolerance for errors, but requiring low latency) and connectionless requirements of pure data (often utilizing a high, bursty data rate and having a relatively high tolerance to latency but little tolerance for errors).
Attempts have been made to provide a connection-like mechanism via the Internet. One such attempt is the ReSerVation (RSVP) Protocol proposed by some vendors and which allows network capacity to be “reserved” at routers and switches to establish a “virtual” connection through the Internet to better ensure that desired quality of service (QoS) levels will be met for the virtual connection. However, support for RSVP must explicitly be implemented within an application and at each switch and/or router involved in the virtual connection, which has been difficult to achieve to date. Further, there is a significant amount of time and overhead required to set up an RSVP connection which can negate the benefits of an RSVP connection for connections of relatively short duration. Even when implemented, RSVP does not typically result in an efficient usage of network capacity as the maximum anticipated bandwidth and/or network capacity requirements must be reserved for the duration of the connection, even if they are not used, or are not used continuously. Thus, in many circumstances, reserved network resources are sitting idle, or are under utilized, for some portion of time. Further, RSVP does not include any incentive mechanism by which applications/users are encouraged to only make effective use of network resources, i.e.—unreasonable requests for resources can be made by a user or application as there are generally no economic or other disincentives for doing so.
Such difficulties are exacerbated when the links on which the network, or a portion of the network, is implemented involve a multiplexed link of expensive and/or limited bandwidth. In such cases efficient utilization of bandwidth and/or network resources is very important and RSVP or similar strategies have difficulty in meeting desired efficiencies. As used herein, the term multiplex and/or multiplexed link are intended to comprise any system or method by which a link is shared amongst users. Examples of such multiplexed links include wired or wireless links employing multiplexing systems such as TDMA, CDMA, OFDM, FDMA or other arrangements.
A specific prior art example of a communication system providing digital voice transmission over a multiplexed wireless link is a PCS (Personal Communication System) cellular system. Such systems can employ a multiplexing technique such as CDMA, TDMA, hybrid systems such as GSM, or other strategies to allow multiple callers to share the wireless link between the cellular base station and the PCS mobile units in both the upstream (mobile to base station) and downlink (base station to mobile) directions. One popular such system is the CDMA-based IS-95 cellular system in use in North America, South Korea and Japan.
While IS-95 based systems, or the like, have been very successful at handling voice communications, attempts to provide pure data services over such systems have experienced less success. To date, one approach has been that an assignable channel, from a limited set of such channels, must be dedicated to each user to which pure data is to be sent. This does not generally make efficient use of the available IS-95 bandwidth, as data rates and requirements vary much more widely than does a typical voice communication for which the channels were designed.
Other attempts have been made to offer data communication systems which address these problems and which are backward compatible with IS-95, but to date no system has been created which provides effective usage of available, limited, bandwidth on a multiplexed link for data transmissions including voice data and pure data.
It is therefore desired to have a communication structure and method of providing communications, including both voice data and pure data, over wireless or other multiplexed links.